1. Field of the Invention
The present invention relates to an image processing system which processes digital images obtained by photographing with radiations such as X-rays, and more specifically a technology for consecutively arranging plural images within an area having a definite size.
2. Description of the Related Art
For X-ray photography in a medical field, it is conventional to first insert an unexposed film into a cassette and then set an object on the cassette. Next, an instructing operation is carried out for irradiating the object with X-rays. By this operation, the object is irradiated with X-rays emitted from an X-ray tube and the film in the cassette is exposed to the X-rays which have transmitted through the above described object.
In order to reduce an amount of the X-rays irradiating the object for a reason of humanity, an aperture of an X-ray diaphragm incorporated with the X-ray tube is controllable manually (by a user's command from a control unit) or automatically in accordance with a cassette size. Such a function is referred to as “autocollimation”.
In addition to photography which obtains an X-ray photographing image in a cassette as a whole (an X-ray photographing image in a film area), there is carried out photography referred to as division photography which arranges plural X-ray photographing images within a film area.
For the division photography, half an area of a cassette (hereinafter referred to as an “A area”) is first concealed with lead, an image is photographed on a rest half of a cassette (a region not concealed with lead to be hereinafter referred to as a “B area”) and then an image is photographed in the A area which was concealed with lead while concealing the B area with lead. Accordingly, plural X-ray photographing images can be obtained in the cassette as a whole (plural X-ray photographing images in a film area).
On the other hand, there has recently been developed a technology for X-ray photography using sensors such as a solid-state image pickup device and along with the development of this technology, digital X-ray image photographic apparatuses which use computers have gradually been put to practical use.
The digital X-ray image photographic apparatus first receives X-rays having transmitted through an object with a sensor, thereby obtaining electric signals of the above described object. The photographic apparatus converts the electric signals into digital signals, thereby obtaining digital X-ray photographing image signals.
The digital X-ray photographing image signals thus obtained are processed with the computer and then visualized on a display or output to a film.
Since the sensor of the digital X-ray photographic apparatus has a fixed size, the digital X-ray photographing image signals obtained by photography have required information only in a field irradiated with X-rays.
Accordingly, the digital X-ray photographic apparatus arranges is capable of obtaining images similar to those obtained by the above described division photography (plural X-ray photographing images in a film area) by arranging images only in the above described irradiation field within an output area of a certain size. A processing for image arrangement can be performed with the above described computer. The digital X-ray photographic apparatus is capable of transferring a result of the above described processing to a display or a printer for output on the display or a film.
A method for arranging plural images within a definite output area (hereinafter referred to as a “method 1”) is disclosed in Japanese Patent Application (Laid-Open) No. 7-111590 or the like.
The method 1 is a method which enlarges or contracts images at a step of arranging plural images within a definite area (output area).
Furthermore, another method (hereinafter referred to as a “method 2”) is disclosed in U.S. Pat. No. 5,644,611 or the like.
The method 2 is a method which divides a frame into lines and rows on a display, and arranges areas in which radiation image information exists in divided formats (multiple formats) at a stage of arranging images when the radiation image information exists in certain areas and does not exist in other areas.
When plural images are to be consecutively arranged in an output area of a definite size by the method 1 or the method 2, it is more efficient from a view point of a cost as well as those of maintenance of films and images to arrange more images in the above described output area considering that the output area is finally output to a display or a film. In other words, an arrangement of more images in the output area makes it possible to reduce an amount of data to be taken into custody and managed by allowing a film or an image to be output in place of a large number of films or images to be output separately. Accordingly, such an arrangement of images is efficient from the viewpoints of the cost and the maintenance.
Even in a case where images are significant as X-ray photographing images but partial deletion of the images is judged as permissible to a certain degree, it may be effective to delete the images before arrangement.
Since the conventional method 1 is configured to enlarge or contract plural images for arrangement in the output area, an observer (a doctor or the like) observes the images in an enlarged or contracted condition when the output area is output to a display or a film for observation. In other words, the conventional method 1 does not allow the doctor to observe images a life size (a size which is not enlarged or contracted). This is seriously problematic for image diagnoses.
Speaking specifically of an actual medical field, for example, where image diagnoses are always carried out by comparison or the like with images of the life size, it is necessary to arrange each image of the life size without enlarging or contracting even when plural images are to be arranged consecutively in an output area of a definite size.
However, the conventional method 1 enlarges or contracts each image and arranges the image in the output area, thereby being fearful to constitute causes for erroneous diagnoses and highly problematic when the images in the output area are used for diagnoses.
Furthermore, the conventional method 2 is configured to always arrange the areas having the radiation image information of plural images in the multiple formats (output areas), thereby limiting a number of images to be arranged in the output areas.
That is, the conventional method 2 provides a result of frames which are divided at an equal aspect ratio and allocates an equal divided size to images even when images to be arranged have different areas which are to be displayed and effective for diagnosis, whereby some images have small areas effective for diagnoses and excessive blank areas, and are inefficient.